JP2009104040A - Positive resist composition and pattern forming method using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive resist composition which ensures few defects after development and is capable of forming a pattern having good plasma etching resistance and a pattern forming method using the same, with respect to a positive resist composition suitable for use in an ultramicrolithography process for producing a very-large-scale IC and high-capacity microchips or in other photofabrication processes and a pattern forming method using the same. <P>SOLUTION: The positive resist composition contains a resin (A) obtained by radical polymerization in the presence of a chain transfer agent. The pattern forming method using the same is also provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a positive resist composition suitably used in an ultramicrolithography process such as the manufacture of VLSI and high-capacity microchips and other photo-publishing processes, and a pattern forming method using the same. More specifically, the present invention relates to a positive resist composition capable of forming a high-definition pattern using KrF excimer laser light, electron beam, EUV light, and the like, and a pattern forming method using the same, KrF excimer laser light, The present invention relates to a positive resist composition that can be suitably used for microfabrication of a semiconductor device using an electron beam or EUV light, and a pattern forming method using the same.

Conventionally, in the manufacturing process of semiconductor devices such as IC and LSI, fine processing by lithography using a photoresist composition has been performed.
As a resist suitable for a lithography process using KrF or ArF excimer laser light, electron beam, or EUV light, a chemically amplified resist utilizing an acid-catalyzed reaction is mainly used from the viewpoint of high sensitivity. In the resist, as a main component, a phenolic polymer (hereinafter abbreviated as a phenolic acid-decomposable resin) and an acid that are insoluble or hardly soluble in an antari developer and become soluble in an antari developer by the action of an acid. A chemically amplified resist composition comprising a generator is effectively used.
For example, in Patent Document 1 (US Pat. No. 5,561,194) and the like, as the phenolic acid-decomposable resin, the hydroxyl group of the phenolic resin is partially acid-decomposable acetal group, ketal group, carbonate group, ether. Resins protected with groups, phenolic acid-decomposable resins copolymerized with acid-decomposable acrylate monomers, and the like are known.
However, since the acrylate monomer has a plurality of oxygen atoms, a resist film made of a polymer having an acrylate monomer is likely to be rubbed during plasma etching, making selective etching difficult.
Further, Patent Document 2 (Japanese Patent Application Laid-Open No. 7-209868) discloses a method of copolymerizing a non-degradable monomer such as styrene, but when a monomer such as styrene is copolymerized, Since the hydrophobicity becomes too high, there arises a new problem that development defects are likely to occur.

US Pat. No. 5,561,194 Japanese Patent Laid-Open No. 7-209868

  An object of the present invention is to solve the problems in microfabrication of semiconductor elements using actinic rays or radiation, particularly KrF excimer laser light, electron beam or EUV light, and is good with few defects after alkali development. Another object of the present invention is to provide a positive resist composition capable of forming a pattern having excellent plasma etching resistance and a pattern forming method using the same.

  As a result of intensive studies, the present inventor has found that the above problems can be achieved by the following constitution, and has reached the present invention.

  (1) A positive resist composition comprising a resin (A) obtained by radical polymerization in the presence of a chain transfer agent.

  (2) The resin (A) has a repeating unit represented by the following general formula (I) and a repeating unit represented by the following general formula (II), is insoluble or hardly soluble in an alkali developer, The positive resist composition as described in (1), which is a resin that becomes soluble in an alkali developer by action.

In general formulas (I) and (II):
R ₁ each independently represents a hydrogen atom or a methyl group.
A represents a group capable of leaving by the action of an acid.
m represents 1 or 2.

  (3) The positive resist composition as described in (1) or (2), wherein the chain transfer agent is a linear, branched or cyclic alkylthiol compound.

  (4) The positive resist composition as described in (2) or (3), wherein the resin (A) further has a repeating unit represented by the following general formula (III).

In general formula (III):
R ₁ represents a hydrogen atom or a methyl group.
R ₂ represents a phenyl group or a cyclohexyl group.
n represents an integer of 0 to 2.

  (5) The positive resist composition as described in any one of (2) to (4), wherein the repeating unit represented by the general formula (I) is represented by the following general formula (Ia): object.

  (6) The positive resist composition as described in any one of (2) to (5), wherein the repeating unit represented by the general formula (II) is represented by the following general formula (II-a) object.

In general formula (II-a):
R ₁ represents a hydrogen atom or a methyl group.

  (7) A method for producing a resin for positive resist composition (A), wherein radical polymerization is carried out in the presence of a chain transfer agent.

  (8) A pattern forming method comprising a step of forming a resist film with the positive resist composition according to any one of (1) to (6), exposing and developing the resist film.

  The preferred embodiments of the present invention will be further described below.

  (9) The positive resist composition as described in any one of (1) to (6), further comprising an organic basic compound.

  (10) The positive resist composition as described in any one of (1) to (6) and (9) above, which further contains a surfactant.

  (11) The positive resist composition as described in any one of (1) to (6), (9) and (10), further comprising a solvent.

  (12) The positive resist composition as described in (11), which contains propylene glycol monomethyl ether acetate as a solvent.

  (13) The positive resist composition as described in (12), further containing propylene glycol monomethyl ether as a solvent.

  (14) A pattern forming method comprising a step of forming a resist film with the positive resist composition according to any one of (9) to (13), exposing and developing the resist film.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a positive resist composition capable of forming a pattern having few defects after development and having good plasma etching resistance, and a pattern forming method using the same.

Hereinafter, the compounds used in the present invention will be described in detail.
In addition, in the description of the group (atomic group) in this specification, the description which does not describe substitution and non-substitution includes what has a substituent with what does not have a substituent. For example, the “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).

(A) Resin obtained by radical polymerization in the presence of a chain transfer agent The positive resist composition of the present invention contains a resin (A) obtained by radical polymerization in the presence of a chain transfer agent. To do.
The weight average molecular weight of the resin can be adjusted by the chain transfer agent, the amount of polymerization initiator used, the polymerization temperature, etc. during radical polymerization. For example, the weight average molecular weight can be increased or decreased by increasing or decreasing the amount of polymerization initiator used. Different resins can be obtained. That is, by increasing the amount of the polymerization initiator, the concentration of radically active species having high reactivity in the system is increased, and the termination reaction is likely to proceed, whereby a resin having a low weight average molecular weight can be obtained.
However, when the weight average molecular weight of the resin is adjusted by such a method, the etching resistance of the low molecular weight resin is lowered.
The termination reaction occurs by reaction between radical active species, but the chemical bond formed by this termination reaction is chemically / physically unstable compared to the chemical bond formed by normal radical growth reaction. Since the bond derived from this stop reaction is dissociated during plasma etching, radical active species are regenerated at the polymer end, and the radical decomposition reaction of the polymer proceeds from this radical active species as a starting point.

In the present invention, by using a chain transfer agent, the weight average molecular weight of the resin can be adjusted without increasing the amount of the polymerization initiator. As a result, the number of bonds derived from the termination reaction contained in the resin can be reduced compared to the number contained in the resin produced without using a chain transfer agent, resulting in a decrease in etching resistance. Can be suppressed.
In addition, since the polymerization is initially performed at a relatively low concentration, the termination reaction is unlikely to proceed, and an ultra high molecular weight body that is not preferable for development defect performance is likely to be generated. However, by using a chain transfer agent, the formation of the ultra high molecular weight substance is suppressed, and the development defect performance is also improved.

Examples of the chain transfer agent that can be used in the present invention include, for example, a linear, branched or cyclic alkylthiol compound having 1 to 20 carbon atoms and an alkyl group having 1 to 6 carbon atoms, which may have a substituent. , An alkoxyl group having 1 to 6 carbon atoms, an arylthiol compound having 6 to 20 carbon atoms having halogen, an alkyl group having 1 to 6 carbon atoms, an alkoxyl group having 1 to 6 carbon atoms, and the like. Examples thereof include aryl disulfide compounds. From the viewpoint of etching resistance, a linear, branched or cyclic alkylthiol compound having 1 to 20 carbon atoms is more preferable because it is chemically / physically stable.
Specific examples of the chain transfer agent include ethanethiol, 1-propanethiol, 2-propanethiol, 1-butanethiol, 1-pentanethiol, 2-methyl-2-propanethiol, 1-hexanethiol, 1- Octanethiol, 1-decanethiol, 1-dodecanethiol, p-toluenethiol, m-toluenethiol, o-toluenethiol, benzenethiol, benzoyl disulfide, benzyl disulfide, bis (p-nitrobenzoyl) disulfide, dimethylthiocarbamoyl disulfide And mercaptomethyl acetate, mercaptoethyl acetate and the like.

The resin (A) is preferably a resin that is insoluble or hardly soluble in an alkali developer and becomes soluble in an alkali developer by the action of an acid. The resin main chain or side chain, or the main chain and side chain It is more preferable that the resin has a group that decomposes by the action of an acid to generate an alkali-soluble group (hereinafter also referred to as “acid-decomposable group”).
Alkali-soluble groups include phenolic hydroxyl groups, carboxylic acid groups, fluorinated alcohol groups, sulfonic acid groups, sulfonamido groups, sulfonylimide groups, (alkylsulfonyl) (alkylcarbonyl) methylene groups, (alkylsulfonyl) (alkylcarbonyl) Imido group, bis (alkylcarbonyl) methylene group, bis (alkylcarbonyl) imide group, bis (alkylsulfonyl) methylene group, bis (alkylsulfonyl) imide group, tris (alkylcarbonyl) methylene group, tris (alkylsulfonyl) methylene group A group having
Preferred alkali-soluble groups include carboxylic acid groups, fluorinated alcohol groups (preferably hexafluoroisopropanol), and sulfonic acid groups.
A preferable group as the acid-decomposable group is a group in which the hydrogen atom of these alkali-soluble groups is substituted with a group capable of leaving by the action of an acid.
Examples of the group capable of leaving by the action of an acid include —C (R ₃₆ ) (R ₃₇ ) (R ₃₈ ), —C (R ₃₆ ) (R ₃₇ ) (OR ₃₉ ), —C (R ₀₁ ) ( R ₀₂ ) (OR ₃₉ ) and the like.
In the formula, R _{36 to} R ₃₉ each independently represents an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, or an alkenyl group. R ₃₆ and R ₃₇ may be bonded to each other to form a ring.
R _{01 and} R ₀₂ each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or an alkenyl group.
The acid-decomposable group is preferably a cumyl ester group, an enol ester group, an acetal ester group, a tertiary alkyl ester group or the like. More preferably, it is a tertiary alkyl ester group.
In the present invention, the acid-decomposable group is contained in a repeating unit represented by the following general formula (II), but may be further contained in another repeating unit.

  The resin (A) preferably has a repeating unit represented by the following general formula (I) and a repeating unit represented by the following general formula (II).

In general formulas (I) and (II):
R ₁ each independently represents a hydrogen atom or a methyl group.
A represents a group capable of leaving by the action of an acid.
m represents 1 or 2.

The content of the repeating unit represented by the general formula (I) in the resin (A) is preferably from 5 to 75 mol%, more preferably from 20 to 70 mol%, based on all the repeating units in the resin (A). It is.
It is preferable that the repeating unit represented by the general formula (I) is contained in the above range from the viewpoint of achieving both the adhesion to the substrate and the resolution.

  Hereinafter, although the specific structure of the repeating unit represented by general formula (I) is illustrated, this invention is not limited to this.

  The repeating unit represented by the general formula (I) is particularly preferably a structure represented by the following formula (Ia).

In general formula (II), the group capable of leaving by the action of an acid A is preferably a hydrocarbon group having 4 to 12 carbon atoms, for example, —C (R ₃₆ ) (R ₃₇ ) (R ₃₈ ). In the formula, R _{36 to} R ₃₉ each independently represents an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, or an alkenyl group. R ₃₆ and R ₃₇ may be bonded to each other to form a ring.
The group capable of leaving by the action of the acid A is preferably a t-butyl group, a t-amyl group, a 1-methylcyclohexyl group, or a 2-cyclohexyl-2-propyl group, and more preferably a t-butyl group. More preferred.
The group leaving by the action of the acid of A may further have a substituent. Further, examples of the substituent that may be included include an alkyl group having 1 to 4 carbon atoms, an alkoxyl group, an alkoxycarbonyl group, a carbamoyl group, a cyano group, and a nitro group.

The content of the repeating unit represented by the general formula (II) in the resin (A) is preferably 5 to 50 mol%, more preferably 10 to 40 mol%, based on all repeating units in the resin (A). It is.
Setting the content of the repeating unit represented by the general formula (II) in the above range is preferable from the viewpoint of achieving both a dissolution rate in an alkaline developer and plasma etching resistance.

  Hereinafter, although the specific structure of the repeating unit represented by general formula (II) is illustrated, this invention is not limited to this.

  The repeating unit represented by the general formula (II) is particularly preferably a structure represented by the following formula (II-a).

  The resin (A) can further have a repeating unit represented by the following general formula (III).

In general formula (III):
R ₁ represents hydrogen or a methyl group.
R ₂ represents a phenyl group or a cyclohexyl group.
n represents an integer of 0 to 2.

In the general formula (III), the phenyl group and cyclohexyl group of R ₂ may further have one or more substituents. From the viewpoint of plasma etching resistance, R ₂ is preferably a phenyl group.
Examples of the substituent that the phenyl group and the cyclohexyl group may further include an alkyl group having 1 to 4 carbon atoms, an alkoxyl group, an alkoxycarbonyl group, a carbamoyl group, a cyano group, and a nitro group. Particularly preferred substituents include alkyl groups having 1 to 4 carbon atoms.

The content of the repeating unit represented by the general formula (III) in the resin (A) is preferably 0 to 50 mol%, more preferably 5 to 40 mol%, more preferably 10 to the resin (A). -35 mol%.
When the repeating unit represented by the general formula (III) is in the above range, it is necessary to obtain sufficient rectangular etching pattern due to sufficient plasma etching resistance and dissolution inhibiting effect, and at the same time sufficient solubility of the exposed area. preferable.

  Hereinafter, although the specific structure of the repeating unit represented by general formula (III) is illustrated, this invention is not limited to this.

  The resin (A) can be produced by radical polymerization in the presence of a chain transfer agent. For example, as a general synthesis method, a monomer corresponding to the repeating unit of the resin (A), a chain transfer agent, and a polymerization initiator are dissolved in a solvent and heated to perform polymerization by heating. Examples thereof include a dropping polymerization method in which a solution of a monomer corresponding to the repeating unit of A), a chain transfer agent and a polymerization initiator is added dropwise over 1 to 10 hours, and the dropping polymerization method is preferred.

  The chain transfer agent is preferably used in an amount of 0.1 to 50 mol%, preferably 1 to 30 mol%, particularly preferably 2.5 to 10 mol%, based on the total number of moles of monomers. .

The polymerization initiator is not particularly limited as long as it is generally used as a radical generator. For example, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), Azo compounds such as dimethyl 2,2′-azobisisobutyrate, 1,1′-azobis (cyclohexane-1-carbonitrile), 4,4′-azobis (4-cyanovaleric acid); decanoyl peroxide, lauroyl peroxide , Organic peroxides such as benzoyl peroxide, bis (3,5,5-trimethylhexanoyl) peroxide, succinic acid peroxide, and t-butylperoxy-2-ethylhexanoate are used singly or in combination. be able to.
The usage-amount of a polymerization initiator is normally selected from the range of 0.1-120 mol% with respect to 1 mol of chain transfer agents, Preferably it is 1-50 mol%, More preferably, it is 10-30 mol%.

Examples of the reaction solvent include ethers such as tetrahydrofuran, 1,4-dioxane, diisopropyl ether, ketones such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate, amide solvents such as dimethylformamide and dimethylacetamide, Furthermore, the solvent which melt | dissolves the positive resist composition of this invention like the below-mentioned ethylene glycol monomethyl ether acetate, ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, cyclohexanone is mentioned. More preferably, the polymerization is performed using the same solvent as the solvent used in the positive resist composition of the present invention. Thereby, the generation of particles during storage can be suppressed.
The polymerization reaction is preferably performed in an inert gas atmosphere such as nitrogen or argon.
After the completion of the reaction, the desired resin (A) is recovered by introducing it into a solvent and recovering the powder or solid. The concentration of the reaction is 5 to 50% by mass, preferably 10 to 30% by mass. The reaction temperature is usually 10 ° C to 150 ° C, preferably 30 ° C to 120 ° C, more preferably 60-100 ° C.

The weight average molecular weight (Mw) of the resin (A) is preferably 5,000 or more from the viewpoint of resolution and density-dependent performance. The weight average molecular weight (Mw) is preferably 50,000 or less from the viewpoint of the dissolution rate of the resin (A) itself in alkali, sensitivity, and defect generation.
The dispersity (Mw / Mn) is preferably 1.0 to 3.0, more preferably 1.0 to 2.5, and particularly preferably 1.0 to 2.0.

In the positive resist composition of the present invention, the blending amount of the resin (A) in the entire composition is preferably 60 to 99% by mass, more preferably 80 to 98% by mass in the total solid content.
In the present invention, the resin (A) may be used alone or in combination.

  Although the structure of resin (A) is illustrated below, this invention is not limited to these.

(B) Compound that generates acid upon irradiation with actinic ray or radiation The positive resist composition of the present invention contains a compound that generates acid upon irradiation with actinic ray or radiation (hereinafter also referred to as “acid generator”). To do.
As an acid generator, photo-initiator of photocation polymerization, photo-initiator of photo-radical polymerization, photo-decoloring agent of dyes, photo-discoloring agent, or irradiation with actinic ray or radiation used for micro-resist etc. Known compounds that generate acids and mixtures thereof can be appropriately selected and used.
Examples thereof include diazonium salts, phosphonium salts, sulfonium salts, iodonium salts, imide sulfonates, oxime sulfonates, diazodisulfones, disulfones, and o-nitrobenzyl sulfonates.
Further, a group that generates an acid upon irradiation with these actinic rays or radiation, or a compound in which a compound is introduced into the main chain or side chain of the polymer, such as US Pat. No. 3,849,137,
German Patent No. 3914407, JP-A-63-26653, JP-A-55-164824, JP-A-62-69263, JP-A-63-146038, JP-A-63-163452, JP-A-63-163452. The compounds described in JP-A-62-153853 and JP-A-63-146029 can be used.
Furthermore, compounds capable of generating an acid by light described in US Pat. No. 3,779,778, European Patent 126,712 and the like can also be used.

  Among the compounds that generate an acid upon irradiation with actinic rays or radiation, compounds represented by the following general formulas (ZI), (ZII), and (ZIII) can be exemplified.

In general formula (ZI),
R ₂₀₁ , R ₂₀₂ and R ₂₀₃ each independently represents an organic group.
X ⁻ represents a non-nucleophilic anion.

Preferred examples of the non-nucleophilic anion for X ⁻ include a sulfonate anion, a bis (alkylsulfonyl) amide anion, a tris (alkylsulfonyl) methide anion, BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ^{− and the} like. It is an organic anion having a carbon atom.

  Preferable organic anions include organic anions represented by the following general formulas (AN1) to (AN3).

In general formulas (AN1) to (AN3),
Rc _{1 to} Rc ₃ each independently represents an organic group.

Formula _(AN1) ~ _(AN3), the organic group in Rc 1 to Rc _3, may be mentioned those having 1 to 30 carbon atoms, preferably an alkyl group which may be substituted, an aryl group or a plurality of these, , A single bond, —O—, —CO ₂ —, —S—, —SO ₃ —, —SO ₂ N (Rd ₁ ) — and the like. Further, it may form a ring structure with another bonded alkyl group or aryl group. Rd ₁ represents a hydrogen atom or an alkyl group, and may form a ring structure with the bonded alkyl group or aryl group.
The organic group of Rc _{1 to} Rc ₃ is preferably an alkyl group substituted at the 1-position with a fluorine atom or a fluoroalkyl group, or a phenyl group substituted with a fluorine atom or a fluoroalkyl group. By having a fluorine atom or a fluoroalkyl group, the acidity of the acid generated by light irradiation is increased and the sensitivity is improved. When Rc ₁ has 5 or more carbon atoms, it is preferable that at least one carbon atom is not all hydrogen atoms replaced by fluorine atoms but hydrogen atoms are left, and the number of hydrogen atoms is fluorine atoms. More is more preferable. By not having a perfluoroalkyl group having 5 or more carbon atoms, ecotoxicity is reduced.

In the general formula (ZI), the organic group as R ₂₀₁ , R ₂₀₂ and R ₂₀₃ generally has 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms.
Two members out of R _{201 to} R ₂₀₃ may combine to form a ring structure, and the ring may contain an oxygen atom, a sulfur atom, an ester bond, an amide bond, or a carbonyl group. The two of the group formed by bonding of the R ₂₀₁ to R _203, there can be mentioned an alkylene group (e.g., butylene, pentylene).

Specific examples of the organic group as R ₂₀₁ , R ₂₀₂ and R ₂₀₃ include corresponding groups in the compounds (ZI-1), (ZI-2) and (ZI-3) described later.

In addition, the compound which has two or more structures represented by general formula (Z1) may be sufficient. For example, the general formula at least one of R ₂₀₁ to R ₂₀₃ of a compound represented by (ZI) is, at least one bond with structure of R ₂₀₁ to R ₂₀₃ of another compound represented by formula (ZI) It may be a compound.

  Further preferred examples of the component (Z1) include compounds (ZI-1), (ZI-2) and (ZI-3) described below.

The compound (ZI-1) is at least one of the aryl groups R ₂₀₁ to R ₂₀₃ in formula (ZI), arylsulfonium compound, i.e., a compound having arylsulfonium as a cation.
In the arylsulfonium compound, all of R _{201 to} R ₂₀₃ may be an aryl group, or a part of R _{201 to} R ₂₀₃ may be an aryl group, and the rest may be an alkyl group or a cycloalkyl group.
Examples of the arylsulfonium compound include triarylsulfonium compounds, diarylalkylsulfonium compounds, aryldialkylsulfonium compounds, diarylcycloalkylsulfonium compounds, aryldicycloalkylsulfonium compounds, and the like.
The aryl group of the arylsulfonium compound is preferably an aryl group such as a phenyl group or a naphthyl group, or a heteroaryl group such as an indole residue or a pyrrole residue, more preferably a phenyl group or an indole residue. When the arylsulfonium compound has two or more aryl groups, the two or more aryl groups may be the same or different.
The alkyl group that the arylsulfonium compound has as necessary is preferably a linear or branched alkyl group having 1 to 15 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an n-butyl group, sec- Examples thereof include a butyl group and a t-butyl group.
The cycloalkyl group that the arylsulfonium compound has as necessary is preferably a cycloalkyl group having 3 to 15 carbon atoms, and examples thereof include a cyclopropyl group, a cyclobutyl group, and a cyclohexyl group.
Aryl group, alkyl group of R ₂₀₁ to R _203, cycloalkyl group, an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), an aryl group (for example, 6 to 14 carbon atoms) , An alkoxy group (for example, having 1 to 15 carbon atoms), a halogen atom, a hydroxyl group, or a phenylthio group may be substituted. Preferred substituents are linear or branched alkyl groups having 1 to 12 carbon atoms, cycloalkyl groups having 3 to 12 carbon atoms, linear chains having 1 to 12 carbon atoms,
A branched or cyclic alkoxy group, more preferably an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms. The substituent may be substituted with any one of the three R _{201 to} R ₂₀₃ , or may be substituted with all three. When R _{201 to} R ₂₀₃ are an aryl group, the substituent is preferably substituted at the p-position of the aryl group.

Next, the compound (ZI-2) will be described.
The compound (ZI-2) is, R ₂₀₁ to R ₂₀₃ in formula (ZI) each independently is a compound when it represents an organic group having no aromatic ring. Here, the aromatic ring includes an aromatic ring having a hetero atom.
The aromatic ring-free organic group as R ₂₀₁ to R ₂₀₃ generally has 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms.
R _{201 to} R ₂₀₃ are each independently preferably an alkyl group, a cycloalkyl group, an allyl group, or a vinyl group, more preferably a linear, branched, cyclic 2-oxoalkyl group, an alkoxycarbonylmethyl group, particularly A linear or branched 2-oxoalkyl group is preferred.

The alkyl group as R ₂₀₁ to R ₂₀₃ may be linear, may be either branched, preferably a straight-chain or branched alkyl group (e.g., methyl group having 1 to 10 carbon atoms, an ethyl group, a propyl group, Butyl group, pentyl group). The alkyl group as R ₂₀₁ to R ₂₀₃ is a straight-chain or branched 2-oxoalkyl group, more preferably an alkoxymethyl group.
The cycloalkyl group as R ₂₀₁ to R ₂₀₃ is preferably, and a cycloalkyl group having 3 to 10 carbon atoms (e.g., cyclopentyl, cyclohexyl, norbornyl).
The 2-oxoalkyl group as R _{201 to} R ₂₀₃ may be linear, branched or cyclic, and preferably a group having> C═O at the 2-position of the above alkyl group or cycloalkyl group Can be mentioned.
The alkoxy group in the alkoxycarbonylmethyl group as R ₂₀₁ to R _203, preferably may be mentioned alkoxy groups having 1 to 5 carbon atoms (a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group).
R _{201 to} R ₂₀₃ may be further substituted with a halogen atom, an alkoxy group (for example, having 1 to 5 carbon atoms), a hydroxyl group, a cyano group, or a nitro group.

  The compound (ZI-3) is a compound represented by the following general formula (ZI-3), and is a compound having a phenacylsulfonium salt structure.

In general formula (ZI-3),
R ₁ c to R ₅ c each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, or a halogen atom.
R ₆ c and R ₇ c each independently represents a hydrogen atom, an alkyl group or a cycloalkyl group.
Rx and Ry each independently represents an alkyl group, a cycloalkyl group, an allyl group, or a vinyl group.
R ₁ c to R ₇ Any two or more of c, and Rx and Ry may combine with each other to form a ring structure, the ring structure may contain an oxygen atom, a sulfur atom, an ester bond, an amide bond May be included. R ₁ c to R ₇ Any two or more of c, and as the group Rx and Ry are formed by combined include a butylene group and a pentylene group.
X − represents a non-nucleophilic anion and is the same as X ^{− in} the general formula (ZI).

The alkyl group as R ₁ c to R ₇ c may be either linear or branched, for example, an alkyl group having 1 to 20 carbon atoms, preferably a linear chain having 1 to 12 carbon atoms and A branched alkyl group (for example, a methyl group, an ethyl group, a linear or branched propyl group, a linear or branched butyl group, a linear or branched pentyl group) can be exemplified.
Preferable examples of the cycloalkyl group as R ₁ c to R ₇ c include a cycloalkyl group having 3 to 8 carbon atoms (for example, a cyclopentyl group and a cyclohexyl group).
The alkoxy group as R ₁ c to R ₅ c may be linear, branched or cyclic, for example, an alkoxy group having 1 to 10 carbon atoms, preferably a linear or branched chain having 1 to 5 carbon atoms. Alkoxy groups (for example, methoxy group, ethoxy group, linear or branched propoxy group, linear or branched butoxy group, linear or branched pentoxy group), cyclic alkoxy groups having 3 to 8 carbon atoms (for example, cyclopentyloxy group, cyclohexyl) Oxy group).
Preferably any of R ₁ c to R ₅ c is a linear or branched alkyl group, a cycloalkyl group or a linear, branched or cyclic alkoxy group, more preferably the R ₁ c to R ₅ c atoms The sum of the numbers is 2-15. Thereby, solvent solubility improves more and generation | occurrence | production of a particle is suppressed at the time of a preservation | save.

The alkyl group as Rx and Ry, there can be mentioned the same alkyl groups as R ₁ c~R ₇ c. The alkyl group as Rx and Ry is more preferably a linear or branched 2-oxoalkyl group or an alkoxymethyl group.
The cycloalkyl group as Rx and Ry may be the same as the cycloalkyl group of R ₁ c~R ₇ c. The cycloalkyl group as Rx and Ry is more preferably a cyclic 2-oxoalkyl group.
Examples of the linear, branched, or cyclic 2-oxoalkyl group include a group having> C═O at the 2-position of the alkyl group or cycloalkyl group as R ₁ c to R ₇ c.
The alkoxy group in the alkoxycarbonylmethyl group may be the same as the alkoxy group as R ₁ c~R ₅ c.
Rx and Ry are preferably alkyl groups having 4 or more carbon atoms, more preferably 6 or more, and still more preferably 8 or more.

In the general formulas (ZII) and (ZIII),
R ₂₀₄ to R ₂₀₇ each independently represents an aryl group, an alkyl group or a cycloalkyl group.
The aryl group of R ₂₀₄ to R _207, a phenyl group, a naphthyl group, more preferably a phenyl group.
The alkyl group as R ₂₀₄ to R ₂₀₇ may be linear, it may be either branched, preferably a straight-chain or branched alkyl group (e.g., methyl group having 1 to 10 carbon atoms, an ethyl group, a propyl Group, butyl group, pentyl group).
The cycloalkyl group as R ₂₀₄ to R ₂₀₇ is preferably, and a cycloalkyl group having 3 to 10 carbon atoms (e.g., cyclopentyl, cyclohexyl, norbornyl).
R ₂₀₄ to R ₂₀₇ may have a substituent. The R ₂₀₄ to R ₂₀₇ are substituents which may have, for example, an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), an aryl group (e.g., 6 carbon atoms 15), alkoxy groups (for example, having 1 to 15 carbon atoms), halogen atoms, hydroxyl groups, phenylthio groups and the like.
X ⁻ represents a non-nucleophilic anion, and examples thereof include the same non-nucleophilic anion as X ^{− in} formula (ZI).

  Among the compounds that generate an acid upon irradiation with actinic rays or radiation, compounds represented by the following general formulas (ZIV), (ZV), and (ZVI) can be further exemplified.

In general formulas (ZIV) to (ZVI),
Ar ₃ and Ar ₄ each independently represents an aryl group.
R ₂₀₈ represents an alkyl group, a cycloalkyl group, or an aryl group.
R ₂₀₉ and R ₂₁₀ each independently represents an alkyl group, a cycloalkyl group, an aryl group, or an electron-withdrawing group. R ₂₀₉ is preferably an aryl group. R ₂₁₀ is preferably an electron-withdrawing group, and more preferably a cyano group or a fluoroalkyl group.
A represents an alkylene group, a cycloalkylene group, an alkenylene group or an arylene group.

  Specific examples of the acid generator are shown below, but are not limited thereto.

An acid generator can be used individually by 1 type or in combination of 2 or more types. When two or more types are used in combination, it is preferable to combine two types of compounds that generate two types of organic acids that differ in the total number of atoms other than hydrogen atoms by two or more.
The content of the acid generator in the composition is preferably from 0.1 to 20% by mass, more preferably from 0.5 to 10% by mass, and even more preferably from 1 to 20% by mass, based on the total solid content of the positive resist composition. 7% by mass.

Organic Basic Compound The positive resist composition of the present invention preferably contains an organic basic compound. The organic basic compound is preferably a compound that is more basic than phenol. The molecular weight of the organic basic compound is usually 100 to 900, preferably 150 to 800, and more preferably 200 to 700. Further, nitrogen-containing basic compounds are particularly preferable.
Preferred nitrogen-containing basic compounds are compounds having structures of the following formulas (CI) to (CV) as a preferred chemical environment. Formulas (CII) to (CV) may be part of a ring structure.

Here, R ₂₅₀ , R ₂₅₁ and R ₂₅₂ may be the same or different and are a hydrogen atom, an alkyl group (preferably having 1 to 20 carbon atoms), a cycloalkyl group (preferably having 3 to 20 carbon atoms) or an aryl group. (Preferably having 6 to 20 carbon atoms), and R ₂₅₁ and R ₂₅₂ may combine with each other to form a ring.

  The alkyl group may be unsubstituted or have a substituent. Examples of the alkyl group having a substituent include an aminoalkyl group having 1 to 6 carbon atoms and a hydroxyalkyl group having 1 to 6 carbon atoms. Is preferred.

R ₂₅₃ , R ₂₅₄ , R ₂₅₅ and R ₂₅₆ may be the same or different and each represents an alkyl group having 1 to 6 carbon atoms.

  Further preferred compounds are nitrogen-containing basic compounds having two or more nitrogen atoms of different chemical environments in one molecule, and particularly preferably both a substituted or unsubstituted amino group and a ring structure containing a nitrogen atom. Or a compound having an alkylamino group.

  Further, at least one nitrogen-containing compound selected from an amine compound having a phenoxy group, an ammonium salt compound having a phenoxy group, an amine compound having a sulfonic acid ester group, and an ammonium salt compound having a sulfonic acid ester group can be exemplified. .

As the amine compound, a primary, secondary or tertiary amine compound can be used, and an amine compound in which at least one alkyl group is bonded to a nitrogen atom is preferable. The amine compound is more preferably a tertiary amine compound. As long as at least one alkyl group (preferably having 1 to 20 carbon atoms) is bonded to a nitrogen atom, the amine compound has an cycloalkyl group (preferably having 3 to 20 carbon atoms) or an aryl group (preferably having 3 to 20 carbon atoms). Preferably C6-C12) may be bonded to a nitrogen atom. The amine compound preferably has an oxygen atom in the alkyl chain and an oxyalkylene group is formed. The number of oxyalkylene groups is one or more in the molecule, preferably 3 to 9, and more preferably 4 to 6. Among the oxyalkylene groups, an oxyethylene group (—CH ₂ CH ₂ O—) or an oxypropylene group (—CH (CH ₃ ) CH ₂ O— or —CH ₂ CH ₂ CH ₂ O—) is preferable, and more preferably oxy Ethylene group.

As the ammonium salt compound, a primary, secondary, tertiary, or quaternary ammonium salt compound can be used, and an ammonium salt compound in which at least one alkyl group is bonded to a nitrogen atom is preferable. As long as at least one alkyl group (preferably having 1 to 20 carbon atoms) is bonded to a nitrogen atom, the ammonium salt compound has a cycloalkyl group (preferably having 3 to 20 carbon atoms) or an aryl group in addition to the alkyl group. (Preferably having 6 to 12 carbon atoms) may be bonded to a nitrogen atom. The ammonium salt compound preferably has an oxygen atom in the alkyl chain and an oxyalkylene group is formed. The number of oxyalkylene groups is one or more in the molecule, preferably 3 to 9, and more preferably 4 to 6. Among the oxyalkylene groups, an oxyethylene group (—CH ₂ CH ₂ O—) or an oxypropylene group (—CH (CH ₃ ) CH ₂ O— or —CH ₂ CH ₂ CH ₂ O—) is preferable, and more preferably oxy Ethylene group. Examples of the anion of the ammonium salt compound include halogen atoms, sulfonates, borates, and phosphates. Among them, halogen atoms and sulfonates are preferable. As the halogen atom, chloride, bromide, and iodide are particularly preferable. As the sulfonate, an organic sulfonate having 1 to 20 carbon atoms is particularly preferable. Examples of the organic sulfonate include alkyl sulfonates having 1 to 20 carbon atoms and aryl sulfonates. The alkyl group of the alkyl sulfonate may have a substituent, and examples of the substituent include fluorine, chlorine, bromine, alkoxy groups, acyl groups, and aryl groups. Specific examples of the alkyl sulfonate include methane sulfonate, ethane sulfonate, butane sulfonate, hexane sulfonate, octane sulfonate, benzyl sulfonate, trifluoromethane sulfonate, pentafluoroethane sulfonate, and nonafluorobutane sulfonate. Examples of the aryl group of the aryl sulfonate include a benzene ring, a naphthalene ring, and an anthracene ring. The benzene ring, naphthalene ring and anthracene ring may have a substituent, and the substituent is preferably a linear or branched alkyl group having 1 to 6 carbon atoms or a cycloalkyl group having 3 to 6 carbon atoms. Specific examples of the linear or branched alkyl group and cycloalkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, i-butyl, t-butyl, n-hexyl, cyclohexyl and the like. Examples of the other substituent include an alkoxy group having 1 to 6 carbon atoms, a halogen atom, cyano, nitro, an acyl group, and an acyloxy group.

  The amine compound having a phenoxy group and the ammonium salt compound having a phenoxy group are those having a phenoxy group at the terminal opposite to the nitrogen atom of the alkyl group of the amine compound or ammonium salt compound. The phenoxy group may have a substituent. Examples of the substituent of the phenoxy group include an alkyl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, a carboxyl group, a carboxylic acid ester group, a sulfonic acid ester group, an aryl group, an aralkyl group, an acyloxy group, and an aryloxy group. Etc. The substitution position of the substituent may be any of the 2-6 positions. The number of substituents may be any in the range of 1 to 5.

It is preferable to have at least one oxyalkylene group between the phenoxy group and the nitrogen atom. The number of oxyalkylene groups is one or more in the molecule, preferably 3 to 9, and more preferably 4 to 6. Among the oxyalkylene groups, an oxyethylene group (—CH ₂ CH ₂ O—) or an oxypropylene group (—CH (CH ₃ ) CH ₂ O— or —CH ₂ CH ₂ CH ₂ O—) is preferable, and more preferably oxy Ethylene group.

  In the amine compound having a sulfonic acid ester group and the ammonium salt compound having a sulfonic acid ester group, the sulfonic acid ester group may be any of alkyl sulfonic acid ester, cycloalkyl group sulfonic acid ester, and aryl sulfonic acid ester. In the case of an alkyl sulfonic acid ester, the alkyl group has 1 to 20 carbon atoms, and in the case of a cycloalkyl sulfonic acid ester, the cycloalkyl group has 3 to 20 carbon atoms in the case of an aryl sulfonic acid ester. The group preferably has 6 to 12 carbon atoms. The alkyl sulfonic acid ester, cycloalkyl sulfonic acid ester, and aryl sulfonic acid ester may have a substituent. Examples of the substituent include a halogen atom, a cyano group, a nitro group, a carboxyl group, a carboxylic acid ester group, a sulfone group. Acid ester groups are preferred.

It is preferable to have at least one oxyalkylene group between the sulfonate group and the nitrogen atom. The number of oxyalkylene groups is one or more in the molecule, preferably 3 to 9, and more preferably 4 to 6. Among the oxyalkylene groups, an oxyethylene group (—CH ₂ CH ₂ O—) or an oxypropylene group (—CH (CH ₃ ) CH ₂ O— or —CH ₂ CH ₂ CH ₂ O—) is preferable, and more preferably oxy Ethylene group.

  Preferred organic basic compounds include guanidine, aminopyridine, aminoalkylpyridine, aminopyrrolidine, indazole, imidazole, pyrazole, pyrazine, pyrimidine, purine, imidazoline, pyrazoline, piperazine, aminomorpholine, aminoalkylmorpholine and the like. . These may have a substituent, and preferred substituents include amino group, aminoalkyl group, alkylamino group, aminoaryl group, arylamino group, alkyl group, alkoxy group, acyl group, acyloxy group, aryl Group, aryloxy group, nitro group, hydroxyl group, cyano group and the like.

  Particularly preferred organic basic compounds include guanidine, 1,1-dimethylguanidine, 1,1,3,3-tetramethylguanidine, imidazole, 2-methylimidazole, 4-methylimidazole, N-methylimidazole, 2-phenyl. Imidazole, 4,5-diphenylimidazole, 2,4,5-triphenylimidazole, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, 2-dimethylaminopyridine, 4-dimethylaminopyridine, 2-diethylaminopyridine 2- (aminomethyl) pyridine, 2-amino-3-methylpyridine, 2-amino-4-methylpyridine, 2-amino-5-methylpyridine, 2-amino-6-methylpyridine, 3-aminoethylpyridine 4-aminoethylpyridine, 3-aminopi Lysine, piperazine, N- (2-aminoethyl) piperazine, N- (2-aminoethyl) piperidine, 4-amino-2,2,6,6-tetramethylpiperidine, 4-piperidinopiperidine, 2-imino Piperidine, 1- (2-aminoethyl) pyrrolidine, pyrazole, 3-amino-5-methylpyrazole, 5-amino-3-methyl-1-p-tolylpyrazole, pyrazine, 2- (aminomethyl) -5-methyl Examples include, but are not limited to, pyrazine, pyrimidine, 2,4-diaminopyrimidine, 4,6-dihydroxypyrimidine, 2-pyrazoline, 3-pyrazoline, N-aminomorpholine, N- (2-aminoethyl) morpholine. Is not to be done.

  A tetraalkylammonium salt type nitrogen-containing basic compound can also be used. Of these, tetraalkylammonium hydroxide having 1 to 8 carbon atoms (tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra- (n-butyl) ammonium hydroxide, etc.) is particularly preferable. These nitrogen-containing basic compounds are used alone or in combination of two or more.

  The use ratio of the acid generator and the organic basic compound in the composition is preferably organic basic compound / acid generator (molar ratio) = 0.01-10. That is, the molar ratio is preferably 10 or less from the viewpoint of sensitivity and resolution, and is preferably 0.01 or more from the viewpoint of suppressing the reduction in resolution due to the thickening of the resist pattern over time until post-exposure heat treatment. The organic basic compound / acid generator (molar ratio) is more preferably 0.05 to 5, and still more preferably 0.1 to 3.

Surfactant In the present invention, surfactants can be used, which are preferable from the viewpoints of film forming property, pattern adhesion, development defect reduction, and the like.

Specific examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene alkyl ethers such as polyoxyethylene oleyl ether, polyoxyethylene octylphenol ether, polyoxyethylene Polyoxyethylene alkyl allyl ethers such as nonylphenol ether, polyoxyethylene / polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate Sorbitan fatty acid esters such as rate, polyoxyethylene sorbitan monolaurate, polyoxyethylene Nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters such as bitane monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, Ftop EF301, EF303, EF352 (manufactured by Shin-Akita Kasei Co., Ltd.), MegaFuck F171, F173 (manufactured by Dainippon Ink and Chemicals), Florad FC430, FC431 (manufactured by Sumitomo 3M), Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.), Troysol S-366 (manufactured by Troy Chemical Co., Ltd.), etc. Hexane polymer KP341 (manufactured by Shin-Etsu Chemical Co.) and acrylic or methacrylic acid-based (co) polymer Polyflow No. 75, no. 95 (manufactured by Kyoeisha Yushi Chemical Co., Ltd.).

As the surfactant, any one of fluorine-based and / or silicon-based surfactants (fluorine-based surfactant and silicon-based surfactant, surfactant containing both fluorine atom and silicon atom), or two kinds of surfactants It is preferable to contain the above.
As these surfactants, for example, JP-A-62-36663, JP-A-61-226746, JP-A-61-226745, JP-A-62-170950, JP-A-63-34540 No. 7, JP-A-7-230165, JP-A-8-62834, JP-A-9-54432, JP-A-9-5988, JP-A 2002-277862, US Pat. No. 5,405,720. No. 5,360,692, No. 5,529,881, No. 5,296,330, No. 5,543,098, No. 5,576,143, No. 5,294,511, No. 5,824,451. The following commercially available surfactants can also be used as they are.
Examples of commercially available surfactants that can be used include EFTOP EF301 and EF303 (manufactured by Shin-Akita Kasei Co., Ltd.), Florard FC430 and 431 (manufactured by Sumitomo 3M Co., Ltd.), MegaFuck F171, F173, F176, F189, and R08. (Dainippon Ink Chemical Co., Ltd.), Surflon S-382, SC101, 102, 103, 104, 105, 106 (Asahi Glass Co., Ltd.), Troisol S-366 (Troy Chemical Co., Ltd.), etc. Fluorine type surfactant or silicon type surfactant can be mentioned. Polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co., Ltd.) can also be used as a silicon-based surfactant.

  In addition to the known surfactants described above, the surfactant is derived from a fluoroaliphatic compound produced by a telomerization method (also called telomer method) or an oligomerization method (also called oligomer method). A surfactant using a polymer having a fluoroaliphatic group can be used. The fluoroaliphatic compound can be synthesized by the method described in JP-A-2002-90991.

  As the polymer having a fluoroaliphatic group, a copolymer of a monomer having a fluoroaliphatic group and (poly (oxyalkylene)) acrylate and / or (poly (oxyalkylene)) methacrylate is preferable and distributed irregularly. Or may be block copolymerized. Examples of the poly (oxyalkylene) group include a poly (oxyethylene) group, a poly (oxypropylene) group, a poly (oxybutylene) group, and the like, and a poly (oxyethylene, oxypropylene, and oxyethylene group). A unit having different chain lengths in the same chain length, such as a block linked body) or a poly (block linked body of oxyethylene and oxypropylene) group, may be used. Furthermore, a copolymer of a monomer having a fluoroaliphatic group and (poly (oxyalkylene)) acrylate (or methacrylate) is not only a binary copolymer but also a monomer having two or more different fluoroaliphatic groups, Further, it may be a ternary or higher copolymer obtained by simultaneously copolymerizing two or more different (poly (oxyalkylene)) acrylates (or methacrylates).

Examples of commercially available surfactants include Megafac F178, F-470, F-473, F-475, F-476, and F-472 (Dainippon Ink Chemical Co., Ltd.). Further, a copolymer of an acrylate (or methacrylate) having a C ₆ F ₁₃ group and (poly (oxyalkylene)) acrylate (or methacrylate), an acrylate (or methacrylate) having a C ₆ F ₁₃ group and (poly (oxy) (Ethylene)) acrylate (or methacrylate) and (poly (oxypropylene)) acrylate (or methacrylate) copolymer, acrylate (or methacrylate) and (poly (oxyalkylene)) acrylate having C ₈ F ₁₇ groups (or Copolymer of acrylate (or methacrylate), (poly (oxyethylene)) acrylate (or methacrylate), and (poly (oxypropylene)) acrylate (or methacrylate) having a C ₈ F ₁₇ group Coalesce, etc. Can.

The amount of the surfactant used is preferably 0.0001 to 2% by mass, more preferably 0.001 to 1% by mass, based on the total amount of the positive resist composition (excluding the solvent).
The surfactant may be added singly or in several combinations.

Solvent The positive resist composition of the present invention is dissolved in a solvent that dissolves each of the above components and coated on a support. The solid content concentration of all resist components is usually preferably 2 to 30% by mass, more preferably 3 to 25% by mass.
Solvents used here include ethylene dichloride, cyclohexanone, cyclopentanone, 2-heptanone, γ-butyrolactone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, ethylene glycol monoethyl ether acetate , Propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, toluene, ethyl acetate, methyl lactate, ethyl lactate, methyl methoxypropionate, ethyl ethoxypropionate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, N, N-dimethyl Formamide, dimethyl sulfoxide, N-methylpyrrolidone, tetrahydrofuran and the like are preferable. Or as a mixture thereof may be used.
As a solvent, it is preferable to contain propylene glycol monomethyl ether acetate. Furthermore, it is more preferable to contain propylene glycol monomethyl ether.

Other Additives The positive resist composition of the present invention can further contain a photobase generator, if necessary.

Photobase generator As photobase generators that can be added to the positive resist composition of the present invention, JP-A-4-151156, JP-A-4-162040, JP-A-5-197148, JP-A-5-5995, JP-A-6-59 Examples include compounds described in 194634, 8-146608, 10-83079, and European Patent 622682, specifically, 2-nitrobenzyl carbamate, 2,5-dinitrobenzyl cyclohexyl carbamate, N-cyclohexyl. -4-Methylphenylsulfonamide, 1,1-dimethyl-2-phenylethyl-N-isopropylcarbamate and the like can be preferably used. These photobase generators are added for the purpose of improving the resist shape and the like.

Carboxylic Acid Generator A compound that generates a carboxylic acid upon irradiation with actinic rays or radiation (hereinafter also referred to as “carboxylic acid generator”) may be used.
The carboxylic acid generator is preferably a compound represented by the following general formula (E).

In the general formula (E), R _{21 to} R ₂₃ each independently represents an alkyl group, a cycloalkyl group, an alkenyl group or an aryl group, and R ₂₄ represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group or Represents an aryl group, and Z represents a sulfur atom or an iodine atom. When Z is a sulfur atom, p is 1, and when Z is an iodine atom, p is 0.

In the general formula (E), R _{21 to} R ₂₃ each independently represents an alkyl group, a cycloalkyl group, an alkenyl group, or an aryl group, and these groups may have a substituent.
Examples of the substituent that the alkyl group, cycloalkyl group or alkenyl group may have include a halogen atom (a chlorine atom, a bromine atom, a fluorine atom, etc.), an aryl group (a phenyl group, a naphthyl group, etc.), a hydroxy group, An alkoxy group (methoxy group, ethoxy group, butoxy group, etc.) etc. can be mentioned.
Examples of the substituent that the aryl group may have include a halogen atom (chlorine atom, bromine atom, fluorine atom, etc.), nitro group, cyano group, alkyl group (methyl group, ethyl group, t-butyl group, t -Amyl group, octyl group, etc.), hydroxy group, alkoxy group (methoxy group, ethoxy group, butoxy group, etc.) and the like.
R _{21 to} R ₂₃ are preferably each independently an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, or an aryl group having 6 to 24 carbon atoms. And more preferably an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, and an aryl group having 6 to 18 carbon atoms, and particularly preferably an aryl group having 6 to 15 carbon atoms. Each of these groups may have a substituent.

R ₂₄ represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group or an aryl group.
Examples of the substituent that the alkyl group, cycloalkyl group, and alkenyl group may have are the same as those described as examples of the substituent when R ₂₁ is an alkyl group. Examples of the substituent for the aryl group, the R ₂₁ may be the same as those mentioned as examples of the substituent when it is an aryl group.
R ₂₄ is preferably a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 24 carbon atoms, and more Preferably, they are a C1-C18 alkyl group, a C3-C18 cycloalkyl group, and a C6-C18 aryl group, Most preferably, a C1-C12 alkyl group, C3-C3 A cycloalkyl group having 12 carbon atoms and an aryl group having 6 to 15 carbon atoms. Each of these groups may have a substituent.

  Two or more of the cation moieties of formula (E) are bonded by a single bond or a linking group (for example, -S-, -O-, etc.) to form a cation structure having a plurality of cation moieties of formula (E). May be.

The content of the carboxylic acid generator in the positive resist composition of the present invention is preferably 0 to 10% by mass, more preferably 0 to 5% by mass, particularly preferably based on the total solid content of the composition. It is 0-3 mass%. In addition, these compounds that generate carboxylic acid upon irradiation with actinic rays or radiation may be used alone or in combination of two or more.

Antioxidant The resist composition of the present invention may contain an antioxidant.
The antioxidant is for preventing the organic material from being oxidized in the presence of oxygen.

  The antioxidant is not particularly limited as long as it is effective in preventing the oxidation of commonly used plastics, for example, a phenolic antioxidant, an antioxidant made of an organic acid derivative, and a sulfur-containing agent. Examples thereof include antioxidants, amine-based antioxidants, antioxidants composed of amine-aldehyde condensates, and antioxidants composed of amine-ketone condensates. Of these antioxidants, phenol antioxidants and antioxidants composed of organic acid derivatives are used as antioxidants in order to exhibit the effects of the present invention without reducing the function of the resist. Is preferred.

  Here, as the phenolic antioxidant, substituted phenols such as 1-oxy-3-methyl-4-isopropylbenzene, 2,6-di-tert-butylphenol, 2,6-di-tert- Butyl-4-ethylphenol, 2,6-di-tert-butyl-4-methylphenol, 4-hydroxymethyl-2,6-di-tert-butylphenol, butyl-hydroxyanisole, 2- (1-methyl (Cyclohexyl) -4,6-dimethylphenol, 2,4-dimethyl-6-tert-butylphenol, 2-methyl-4,6-dinonylphenol, 2,6-di-tert-butyl-α-dimethylamino- p-cresol, 6- (4-hydroxy-3,5-di-tert-butyl-anilino) 2,4-bisoctyl-thio-1,3,5-triazine, n-octyl Decyl-3- (4′-hydroxy-3 ′, 5′-di-tert-butyl-phenyl) propionate, octylated phenol, aralkyl-substituted phenols, alkylated p-cresol, hindered phenol, etc. Bis, tris, polyphenols such as 4,4′-dihydroxy-diphenyl, methylene-bis (dimethyl-4,6-phenol), 2,2′-methylene-bis- (4-methyl-6-third) -Butylphenol), 2,2'-methylene-bis- (4-methyl-6-cyclohexyl-phenol), 2,2'-methylene-bis- (4-ethyl-6-tert-butylphenol), 4,4 '-Methylene-bis- (2,6-di-tert-butylphenol), 2,2'-methylene-bis- (6-alphamethyl-benzyl- p-cresol), methylene bridged polyhydric alkylphenol, 4,4′-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1-bis- (4-hydroxyphenyl) -cyclohexane, 2,2 '-Dihydroxy-3,3'-di- (α-methylcyclohexyl) -5,5'-dimethyl-diphenylmethane, alkylated bisphenol, hindered bisphenol, 1,3,5-trimethyl-2,4,6-tris (3,5-ditert-butyl-4-hydroxybenzyl) benzene, tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, tetrakis- [methylene-3- (3 ′, 5 '-Di-tert-butyl-4'-hydroxyphenyl) propionate] and the like.

  Preferable specific examples of the antioxidant used in the present invention include 2,6-di-t-butyl-4-methylphenol, 4-hydroxymethyl-2,6-di-t-butylphenol, and 2,2′-methylenebis. (4-methyl-6-t-butylphenol), butylhydroxyanisole, t-butylhydroquinone, 2,4,5-trihydroxybutyrophenone, nordihydroguaiaretic acid, propyl gallate, octyl gallate, lauryl gallate, And isopropyl citrate. Of these, 2,6-di-t-butyl-4-methylphenol, 4-hydroxymethyl-2,6-di-t-butylphenol, butylhydroxyanisole, and t-butylhydroquinone are preferred, and 2,6-diethyl is further preferred. -T-Butyl-4-methylphenol or 4-hydroxymethyl-2,6-di-t-butylphenol is more preferred.

  The content of the antioxidant is preferably 1 ppm or more in the positive resist composition, more preferably 5 ppm or more, still more preferably 10 ppm or more, and further preferably 50 ppm or more. More preferably 100 ppm or more, and particularly preferably 100 to 10,000 ppm. A plurality of antioxidants may be mixed and used.

Film Formation The positive resist composition of the present invention is applied onto a substrate to form a thin film. The thickness of this coating film is preferably 0.05 to 4.0 μm.

An antireflection film may be provided under the resist. As the antireflection film, any of an inorganic film type such as titanium, titanium dioxide, titanium nitride, chromium oxide, carbon, and amorphous silicon, and an organic film type made of a light absorber and a polymer material can be used. The former requires equipment such as a vacuum deposition apparatus, a CVD apparatus, and a sputtering apparatus for film formation. Examples of the organic antireflection film include a condensate of a diphenylamine derivative and a formaldehyde-modified melamine resin described in JP-B-7-69611, an alkali-soluble resin, a light absorber, and maleic anhydride copolymer described in US Pat. No. 5,294,680. A reaction product of a coalescence and a diamine type light absorbing agent, a resin binder described in JP-A-6-186863 and a methylolmelamine thermal crosslinking agent, a carboxylic acid group, an epoxy group and a light-absorbing group described in JP-A-6-118656. An acrylic resin-type antireflection film in the same molecule, a composition comprising methylol melamine and a benzophenone-based light absorber described in JP-A-8-87115, and a low-molecular light absorber added to a polyvinyl alcohol resin described in JP-A-8-179509 And the like.
In addition, as the organic antireflection film, commercially available organic antireflection films such as DUV30 series, DUV-40 series manufactured by Brewer Science, AR-2, AR-3, AR-5 manufactured by Shipley, etc. may be used. it can.
Further, if necessary, an antireflection film can be used as an upper layer of the resist.
Examples of the antireflection film include AQUATAR-II, AQUATAR-III, and AQUATAR-VII manufactured by AZ Electronic Materials.

  In the manufacture of precision integrated circuit elements, the pattern forming process on the resist film is carried out on the substrate (eg, silicon / silicon dioxide coated substrate, glass substrate, ITO substrate, quartz / chromium oxide coated substrate, etc.). A resist pattern is formed by applying a resist composition, forming a resist film, and then irradiating actinic rays or radiation such as KrF excimer laser light, electron beam, EUV light, etc., heating, developing, rinsing and drying. Can be formed.

Examples of the alkaline developer used in development include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia, and primary amines such as ethylamine and n-propylamine. Secondary amines such as diethylamine and di-n-butylamine, tertiary amines such as triethylamine and methyldiethylamine, alcoholamines such as dimethylethanolamine and triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, An aqueous solution (usually 0.1 to 20% by mass) of an alkali such as a quaternary ammonium salt such as choline or a cyclic amine such as pyrrole or piperidine can be used. Furthermore, an appropriate amount of an alcohol such as isopropyl alcohol or a nonionic surfactant may be added to the alkaline aqueous solution.
Among these developers, quaternary ammonium salts are preferable, and tetramethylammonium hydroxide and choline are more preferable.
The pH of the alkaline developer is usually 10-15.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, the content of this invention is not limited by this.

Synthesis Example 1 (Synthesis of Resin (A-7-1))
600 g of ethylene glycol monoethyl ether acetate was placed in a 2 L flask, and the atmosphere was purged with nitrogen at a flow rate of 100 mL / min for 1 hour. In addition, 97.3 g (0.60 mol) of 4-acetoxystyrene, 42.7 g (0.30 mol) of t-butyl methacrylate, 17.6 g (0.10 mol) of benzyl methacrylate, a polymerization initiator V-601 (Wako Pure Chemical Industries, Ltd.) (Made by Co., Ltd.) 2.30 g (0.01 mol) and 1.46 g (0.01 mol) of 1-octyl mercaptan were dissolved in 200 g of ethylene glycol monoethyl ether acetate, and the resulting solution was purged with nitrogen in the same manner as described above. .
A 2 L flask containing ethylene glycol monoethyl ether acetate was heated up to an internal temperature of 80 ° C., and then 2.30 g (0.01 mol) of a polymerization initiator V-601 was added and stirred for 5 minutes. . Thereafter, the monomer mixed solution was added dropwise over 6 hours with stirring. After the dropping, the mixture was further heated and stirred for 2 hours, and then the reaction solution was cooled to room temperature and dropped into 3 L of hexane to precipitate a polymer. The filtered solid was dissolved in 500 ml of acetone, dropped again into 3 L of hexane, and the filtered solid was dried under reduced pressure to obtain 149 g of 4-acetoxystyrene / t-butyl methacrylate / benzyl methacrylate copolymer.
40.0 g of the copolymer obtained above, 40 ml of methanol, 200 ml of 1-methoxy-2-propanol and 1.5 ml of concentrated hydrochloric acid were added to the reaction vessel, heated to 80 ° C. and stirred for 5 hours. The reaction solution was allowed to cool to room temperature and dropped into 3 L of distilled water. The filtered solid was dissolved in 200 ml of acetone, dropped again into 3 L of distilled water, and the filtered solid was dried under reduced pressure to obtain 31.0 g of resin (A-7-1). The weight average molecular weight by GPC was 8000, and the molecular weight dispersity (Mw / Mn) was 1.58.

Synthesis Example 2 (Synthesis of Resin (A-7-4))
Resin (A-7-4) 30. was prepared in the same manner as in Synthesis Example 1 except that the amount of the polymerization initiator V-601 was 9.2 g (0.04 mol) and 1-octyl mercaptan was not added. 5 g was obtained.
The weight average molecular weight by GPC was 8500, and the molecular weight dispersity (Mw / Mn) was 1.71.

  Resins were synthesized under the conditions shown in Table 1 below. In Table 1, resin column, the two letters from the left represent the resin structure. For example, a resin “A-1-1” is a resin having the structure (A-1) exemplified above. Table 1 shows the composition ratio, weight average molecular weight (Mw), and molecular weight dispersity (Mw / Mn) of the resin. The composition ratio (molar ratio) corresponds to the repeating units in the resin structure exemplified above in order from the left.

  Hereinafter, the structures of the resins (Z-1) and (Z-2) in Table 1 are shown.

Examples 1-7 and Comparative Examples 1-4
(Preparation of resist composition)
Resin, acid generator, organic basic compound and surfactant are dissolved in a mixed solvent with propylene glycol monomethyl ether acetate (PGMEA) or propylene glycol monomethyl ether (PGME) (mixing ratio is shown in Table 2), and solid content After preparing a solution having a concentration of 10.0% by mass, the obtained solution was microfiltered with a membrane filter having a 0.1 μm aperture to obtain a resist solution.
Table 2 below shows the resist solutions used for the evaluation. Here, the addition amount (mass%) of each component means the mass% with respect to solid content except a solvent.

[Evaluation]
(Residual film rate (plasma etching resistance))
A positive resist film having a thickness of 0.4 μm is formed on a wafer subjected to HMDS treatment, and then a mixed gas of CF ₄ (10 mL / min), O ₂ (20 mL / min) and Ar (1000 mL / min) is used. Then, plasma etching was performed for 30 seconds at a temperature of 23 ° C. Thereafter, the residual film amount of the resist film was measured, and the value obtained by dividing the resist film by the original film thickness of 0.4 μm and multiplying by 100 was defined as the residual film ratio (%). The larger the remaining film ratio, the better the plasma etching resistance.
(defect)
With a mask pattern having a mask size of 180 nm and a pitch of 360 nm, a 0.18 μm pattern was exposed at 78 locations within the wafer surface with an exposure amount that would yield a 180 nm resist pattern. The number of development defects of the obtained patterned wafer was measured with KLA-2360 manufactured by KLA-Tencor Corporation. In this case, the inspection area was 205 cm ² in total, the pixel size was 0.25 μm, the threshold = 30, and the inspection light was visible light. A value obtained by dividing the obtained numerical value by the inspection area was evaluated as the number of defects (pieces / cm ² ).
The evaluation results are shown in Table 2.

  The abbreviations in the table are shown below.

(Organic basic compounds)
C-1: Dicyclohexylmethylamine C-2: 2,4,6-triphenylimidazole C-3: Tetra- (n-butyl) ammonium hydroxide C-4:

(Surfactant)
D-1: Fluorosurfactant, MegaFuck F-176 (manufactured by Dainippon Ink & Chemicals, Inc.)
D-2: Fluorine / silicone surfactant, MegaFac R08 (manufactured by Dainippon Ink & Chemicals, Inc.)
D-3: Silicon-based surfactant, siloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.)

  From Table 2, it is clear that the positive resist composition of the present invention has few development defects and has sufficient plasma etching resistance.

Claims (8)

  A positive resist composition comprising a resin (A) obtained by radical polymerization in the presence of a chain transfer agent. Resin (A) has a repeating unit represented by the following general formula (I) and a repeating unit represented by the following general formula (II), is insoluble or hardly soluble in an alkali developer, and is alkalinized by the action of an acid. The positive resist composition according to claim 1, wherein the positive resist composition is a resin that is soluble in a developer.

In general formulas (I) and (II):
R ₁ each independently represents a hydrogen atom or a methyl group.
A represents a group capable of leaving by the action of an acid.
m represents 1 or 2.   3. The positive resist composition according to claim 1, wherein the chain transfer agent is a linear, branched or cyclic alkylthiol compound. 4. The positive resist composition according to claim 2, wherein the resin (A) further has a repeating unit represented by the following general formula (III).

In general formula (III):
R ₁ represents a hydrogen atom or a methyl group.
R ₂ represents a phenyl group or a cyclohexyl group.
n represents an integer of 0 to 2. The positive resist composition according to claim 2, wherein the repeating unit represented by the general formula (I) is represented by the following general formula (Ia).

6. The positive resist composition according to claim 2, wherein the repeating unit represented by the general formula (II) is represented by the following general formula (II-a).

In general formula (II-a):
R ₁ represents a hydrogen atom or a methyl group.   A method for producing a resin for positive resist composition (A), wherein radical polymerization is carried out in the presence of a chain transfer agent.   A pattern forming method comprising the steps of forming a resist film with the positive resist composition according to claim 1, exposing and developing the resist film.